1. Field of the Invention
The present invention relates to a display driving circuit and particularly to a display driving circuit with fewer data drivers.
2. Description of the Prior Art
FIG. 1 is a diagram showing a conventional display driving circuit 1. It includes two data drivers 121 and 122, a scan driver 11, a pixel matrix composed of display cells 13, and switches 161 and 162 composed of transistors. Each of the display cells 13 in the odd columns of the pixel matrix receives a data signal through a data line 151 from the data driver 121 or 122. Each of the display cells 13 in the even columns of the pixel matrix receives a data signal through a data line 152 from the data driver 121 or 122. The display cells 13 also receive scan signals through scan lines 14 from the scan driver 11. To reduce the number of the data drivers, data line 151 and 152 are respectively coupled to the display cells 13 in the odd and even column of the pixel matrix share the same data terminal as the data driver through the switches 161 and 162 controlled by signals SW1 and SW2. When one of the scan signals is asserted, the odd and even display cells 13 in the scanned row of the matrix receive the data signal output from the same terminal of the data driver 121 or 122 by turns. In FIG. 1, for example, the number of the data drivers is half of that not using the switches to share the data terminals since each data terminal provides the data signals to two columns of display cells of the pixel matrix.
However, in the conventional display driving circuit, the switching frequency of the switches 161 and 162 is n times the frame rate, wherein n is the number of the columns in the pixel matrix. For example, the switching frequency of the switches in a display having 768 pixel columns and a frame rate of 60 Hz. is 46080 Hz. Such a switching frequency is much higher than that of the thin-film transistors (TFTs) used in the display cells 13. This results in high current stress which degrades the reliability of the circuit.